Fibrous products from thermoplastic polyamide polymers

ABSTRACT

An air pervious, water repellent, self-supporting fibrous mat is produced by spraying a mixture of polyamide polymer and a suitable, rapidly evaporating compatible solvent. The fibrous mats are suitable for use as fabrics, decorative applications, tamper-proof bottle sealers, packaging materials, etc.

iliaited States Patent 1191 Workman 1 FIBROUS PRODUCTS FROMTHERMOPLASTIC POLYAMIDE POLYMERS {75] Inventor: Clayton E. Workman,Minneapolis,

Minn.

[73] Assignee: General Mills, Inc., Minneapolis,

Minn.

[22] Filed: Apr. 20, 1971 211 Appl. No.: 135,682

Related US. Application Data [63] Continuation-impart of Ser. No.741,433, July 1 1968, abandoned.

52 US. Cl 161/169',117/21, 156/622, 156/251, 161/109, 260/33.8, 264/205,128/156,128/517,8/4,8/14,8/17 ,8/178 R 51 1m. c1. B32b 5/02, D04h 1/00[58] Field 61 Search 156/622, 62.4, 62.6; 161/169; 264/205, 290 N;260/4045, 32.6

[5 6] References Cited UNITED STATES PATENTS Manning 161/150 Nov. 113,

2,927,906 3/1960 Schlack 260/326 N 3,016,599 1/1962 Perry 161/1693,256,304 6/1966 Fischer et a1. 260/4045 3,280,140 10/1966 Sharkey260/4045 3,550,806 12/1970 Peerman et a1... 260/4045 3,501,368 3/1970Schabert et a1 1 161/151 3,449,273 6/1969 Kettenring et a1... 260/18 NPrimary ExaminerGeorge F. Lesmes Assistant ExaminerPaul J. ThibodeauAtt0rney-Anthony A. Juettner and Gene 0. Enockson [57] ABSTRACT An airpervious, water repellent, self-supporting fibrous mat is produced byspraying a mixture of poly amide polymer and a suitable, rapidlyevaporating compatible solvent. The fibrous mats are suitable for use asfabrics, decorative applications, tamper-proof bottle sealers, packagingmaterials, etc.

13 Claims, 15 Drawing Figures Patented Nov -.13, 1973 7 Sheets-Sheet 1AT TORN EY Famed 1 Nov .13, 1973 INVENTOR cmrrwv a. h/OAKMflA! gun. Q-

[Sheba-Sheet 2 FIG ATTORNEY Patented Nov .13, 1973 7 Sheets-Sheet 5ATTORNEY Patented Nov .13, 1973 N V E NTO R cmrra z. WGRKMHIY BY 7Sheets-Sheet 4 F l G 4 ATTORNEY Patented Nov .13, 1973 7 Sheets-Sheet 5INVENTOR 40770 2'' MOE/(MIMI ATTORNEY Patented Nov .13, 1973Sheets-Sheet 6 F I' G. 8

' INVENTOR. 044770 E. WORK/M4 l m P ATTOR N EY Patented Nov .13, 1973 7Sheets-Sheet 7 cub 701v 62 Mam M441 ATTO R N E Y FIG. l5

FIBROUS PRODUCTS FROM THERMOPLASTIC POLYAMIDE POLYMERS This applicationis a continuation-in-part of my earlier filed application Ser. No.741,433, filed July 1, 1968 and now abandoned.

This invention relates to fibrous products prepared from polyamides.More specifically, this invention relates to self-supporting fibrousmats which are prepared by spraying a mixture of polyamide polymer and afast evaporating compatible solvent.

It has been known that decorative web-like effects can be obtained byspraying veiling lacquers with a spray gun. In the past, these effectswere obtained by spraying a formulated colored nitrocellulose to apreviously painted base coat of contrasting color. Similar effects havebeen obtained with the use of synthetic rubbers and polyvinylidenechloride. However, these earlier sprayed effects were notself-supporting nor did they appear to be water repellent and airpervious. Likewise, they did not offer the advantages of the polyamides.These earlier applications were used almost exclusively as veilinglacquers sprayed over a substrate to produce decorative effects.

Turning to the drawings, it can be seen that FIGS. 1-5 arephotomicrographs of portions of a selfsupporting fibrous mat prepared inaccordance with this invention.

FIG. 6 shows the fibrous mat bonded to a substrate.

FIG. 7 shows a raincoat made from the fibrous mat.

FIGS. 8 and 9 show a beverage can having the fibrous mat as a sanitarycovering.

FIGS. and 11 show a bottle having a tamper-proof sea] of sprayedpolyamide fibrous mat.

FIGS. 12-15 show the packaging of an object using two layers of thefibrous mat. I

It has now been found that thermoplastic polyamides when dissolved in anappropriate solvent can be sprayed onto a substrate to produce aweb-like effect. This web-like effect will hereinafter be referred to asa fibrous mat since the sprayed mat can be removed for a release typesubstrate and be self-supporting. The fibrous mat is comprised of fibersessentially nonuniform in thickness (or diameter) and length,alternating between areas having a solid cross-sectionwith areas whosecross-section is tubular. The fibers thus have along their length anumber of non-uniform totally enclosed gas pockets (i.e., bubbles).Various of the fibers are interconnected (or bonded) to each other toform air holes in the mat.

As used herein, the term polyamide polymer is intended to includethermoplastic polyamide resins made by the condensation polymerizationof lactams and/or amino acids along with dicarboxylic acids and diaminesincluding conventional dicarboxylic acids such as adipic acid, sebacicacid, etc. as well as the polymerized fatty acids. Polyamide polymers asused herein is also intended to include the thermoplastic polyamideresins prepared by the condensation polymerization of diamines andpolymerized fat acids or polymerized fat acids in combination withconventional dicarboxylic acids.

When practicing this invention, one of the preferred embodimentsincludes the dissolution of a polyamide, which is the reaction productof a polymerized fatty acid and diamine as defined herein, in anappropriate, rapid evaporating solvent such as chloroform, methylenechloride, etc. This mixture is then sprayed under pressure, preferablyat least 3 lb. gage pressure, from a conventional spray gun. Generally,the resin concentration in the solvent will be about 5 to 25 percent,preferably 15 to 20 percent by weight of resin. However, the resincontent will vary with the type of spray equipment, solvent,application, and solubility of the polyamide in the solvent. When theabove mixture is sprayed, as indicated, onto a substrate or a releasetype support such as tetr'afluoroethylene fluorocarbon resin Tefloncoated glass cloth, a fibrous mat can be formed. This mat will be airpervious and water repellent. It will be evident to those skilled in theart that optimum spraying conditions, i.e., pressure, nozzle selection,mat thickness, etc. will be readily apparent through a few optimum spraytesting patterns.

A number of uses for the sprayed polyamide fibrous mat are illustratedin the drawings. The photomicrograph, FIG. 1, is approximately a 12Xenlargement of a portion of the self-supporting fibrous mat as preparedin Example I. It can be seen that the mat has fibers, 1, and a number ofsmall openings, 2, which will allow for the passage of air. Since thefibers are hydrophobic, the mat is water repellent.

FIGS. 2-5 are further photomicrographs of portions of the fibrous mat asprepared in Example I (enlargements of X, 250x, 250x and 1,000X,respectively). It can be seen that the mats have fibers, l, openings, 2,bubbles within the fibers, 3, interconnected fibers, 4, and air holes,5, formed by the interconnection of the fibers. In the photomicrographsof FIGS. 2-5, 1 mm. equals 6.6, 4, 4, and 1 micron, respectively. Thusthe large bubble, 3, of FIG. 4 has a longest dimension of 286 microns,the diameter of the smallest fiber, 1, of FIG. 5 is 1 micron and thediameter of the smallest bubble, 3, of FIG. 5 is also 1 micron.

FIG. 6 shows the sprayed fibrous mat, 6, bonded to a substrate, 7.

FIG. 7 is a drawing of a raincoat prepared from cotton cloth, 8, ontowhich was sprayed the fibrous mat, 9, prior to cutting and sewing of theraincoat.

FIG. 8 shows a beverage can, 10, which has the fibrous mat, ll, sprayedover the top of the can to give a sanitary covering. In FIG. 9, thefibrous mat, H1, is partially peeled from the top of the can.

FIG. 10 shows a bottle, 12, which has been made tamper-proof by havingthe cap and bottle neck sprayed with the fibrous mat, 13. FIG. 11 showsthe cap removed from the bottle and the tamper-proof seal broken,leaving jagged fibers, l4, wherever the seal has been broken.

FIG. 12 shows an object, 15, placed between two layers of the fibrousmat, I6. FIG. 13 shows the shearing by means of a scissors, 17, of bothlayers of the fibrous mat enclosing the object. FIG. 14 shows theobject, 15, totally enclosed by the sheared fibrous mat layers, 16,which are joined by the shearing action along their outer edges. FIG. 15is an end view along line 18-11% of the packaged object showing that thefibrous layers have a bond, 19, due to the shearing action.

As indicated above a variety of polyamide polymers are' useful in thepresent invention. These include the condensation products of lactamsand/or amino acids along with dicarboxylic acids and diamines. Variousof these products are readily commercially available. They are normallydefined by the weight percent content of the condensates of theirindividual starting materials. Thus the Elvamid resin used in ExampleXII-is prepared by the condensation polymerization of caprolactam,hexamethylene diamine, adipic acid and se bacic acid with the resultingcomposition being defined as follows:

hexamethylene diarnine and sebacic acid) Likewise whenll-aminoundecanoic acid is used as a component, it is identified asnylon l l (i.e., the condensate of l l-aminoundecanoic acid). Thesepolyamides are prepared using known techniques which include the use ofheat to amide forming temperatures-i.e., above about lOO to 300 C., suchas 200250C.

Suitable dicarboxylic acids have the general formula HOOC-R-COOH where Ris an aliphatic or cycloaliphatic radical having 3-48 carbon atoms.Simple dibasic acids include glutaric, pimelic, adipic, sebacic,suberic, azelaic acid, etc. Diamines suitable in preparing thepolyamides useful in the present invention are also illustratedhereinbelow following the description of the polymeric fat acid basedpolyamides and the polymeric fat acid reactants.

Other suitable polyamides are the reaction products of diamines andpolymerized fatty acids or polymerized fatty acids in combination withsimple dibasic acids. The polymeric fat acids which may be employed inpreparing the polyamides are those resulting from the polymerization ofdrying or semidrying oils or the free fat acids or simple alcohol estersof these fat acids. The term fat acids" is intended to includesaturated, ethylenically unsaturated and acetylenically unsaturated,naturally occurring, and any synthetic monobasic ali phatic acidscontaining from 16 to 24 carbon atoms. The term polymeric fat acid"refers to polymerized fat acids. The term polymeric fat radical" refersto the hydrocarbon radical of a polymerized fat acid, and is generic tothe divalent, trivalent, and other polyvalent hydrocarbon radicals ofdimerized fat acids, trimerized fat acids and higher polymers of fatacids. The divalent and trivalent hydrocarbon radicals are referred toherein as dimeric fat radical and trimeric fat radical" respectively.

The saturated, ethylenically unsaturated, and acetylenically unsaturatedfat acids are generally polymerized by somewhat different techniques,but because of the functional similarity of the polymerization product,they are generally referred to as polymeric fat acids.

Saturated fat acids are difficult to polymerize but polymerization canbe obtained at elevated temperatures with a peroxidic catalyst such asditertiarybutyl peroxide. Because of the generally low yields ofpolymeric products, these materials are not current commerciallysignificant. Suitable saturated fat acids include branched and straightacids such as caprylic acid, pelargonic acid, capric acid, lauric acid,myristic acid, palmitic acid, isopalmitic acid, stearic acid, arachidicacid, behenic acid, and lignoceric acid.

The ethylenically unsaturated acids are much more readily polymerized.Suitable polymerization methods are disclosed in U. S. Pat. Nos.3,256,304 and 3,157,681. The ethylenically unsaturated acids can bepolymerized using both catalytic or non-catalytic polymerizationtechniques.

The preferred aliphatic acids are the monoand polyulefinicallyunsaturated 18 carbon atom acids. Representative of such acids are4-octadecenoic. 5- octadecenoic, 6-octadecenoic (petroselinicl, 7octadecenoic, 8-octadecenoic, cis-9-octadecenoic (oleicl.trans-9-octadecenoic (elaidic), l loctadecenoic (vaccenic),lZ-octadecenoic and the like. Representative octadecadienoic acids are9,l2octadecadienoic (linoleic), 9,l l-octadecadienoic. l0.l 2-octadecadienoic. l2,l5octadecadienoic and the like. Representativeoctadecatrienoic acids are 9.l 2.1 5- octadecatrienoic (linolenic).6.9.l2-octadecatrienoic, 9.1 l.l3-octadecatrienoic (eleostearic).10.12.14- octadecatrienoic (pseudo-eleostearicl and the like. Arepresentative 1 8 carbon atom acid having more than three double bondsis moroctic acid which is indicated to be 4.8,l2,lS-octadecatetraienoicacid. Representative of the less preferred (not as readily availablecommercially) acids are: 7-hexadecenoic. 9-hexadecenoic (palmitoleic),9-eicosenoic (gadoleic), l l-eicosenoic. 6,l(l,l4-hexadecatrienoic(hiragonic), 4,8,12,16- eicosatetraenoic, 4,8.l2.l5.l8-eicosapentanoic(timnodonic). l3-docosenoic (erucicf l l-docosenoic (cetoleic), and thelike.

The polymerization of the described ethylenically unsaturated acidsyields relatively complex products which usually contain a predominantportion of dimer ized acids, a smaller quantity of trimerized and higherpolymeric acids and some residual monomers. The dimerized acids,generally containing 32 to 44 carbon atoms can be obtained in reasonablyhigh purity from the polymerization products by vacuum distillation atlow pressures, solvent extraction, or other known separation procedures.It is preferred to have a dimer acid content of at least percent, morepreferably percent. The polymerization product varies somewhat dependingon the starting fat acid or mixture thereof and the polymerizationtechnique employedi.e., thermal, catalytic, particular catalyst,conditions of pressure, temperature, etc. Likewise, the nature of thedimerized acids separated from the polymerization product also dependssomewhat on these factors although such acids are functionally similar.

As a practical matter, the dimeric fat acids are preferably prepared bythe polymerization of mixtures of acids (or the simple aliphatic alcoholestersi.e., methyl esters) derived from the naturally occurring dryingand semi-drying oils or similar materials. Suitable drying orsemi-drying oils include soybean, linseed, tung, perilla, oiticia,cottonseed, corn, sunflower, dehydrated caster oil and the like. Also,the most readily available acid is linoleic or mixtures of the same witholeic, linolenic and the like. Thus, it is preferred to use as thestarting materials, mixtures which are rich in linoleic acid. Anespecially preferred material is the mixture of acids obtained from talloil which mixture is composed of approximately 4045 percent linoleic and5055 percent oleic.

Reference has been made hereinabove to the monomeric, dimeric andtrimeric fat acids present in the polymeric fat acids. The amounts ofmonomeric fat acids, often referred to as monomer, dimeric fat acids,often referred to as dimer, and trimeric or higher polymeric fat acids,often referred to as trimer, present in polymeric fat acids may bedetermined analytically by gasliquid chromatography of the correspondingmethyl esters. Unless otherwise indicated herein, this analytical methodwas used in the analysis of the polymeric fat acids employed in thisinvention. Another method of determination is a micromoleculardistillation analytical method. This method is that of R. F. Paschke et.al., J. Am. Oil Chem. 800., XXX! (No. l), 5, (1954), wherein thedistillation is carried out under high vacuum (below 5 microns) and themonomeric fraction is calculated from the weight of product distillingat 155 C., the dimeric fraction calculated from that distilling between155 and 250 C., and the trimeric (or higher) fraction is calculatedbased on the residue. When the gas-liquid chromatography technique isemployed, a portion intermediate between monomeric fat acids and dimericfat acids is seen, and is termed herein merely as intermediate, sincethe exact nature thereof is not fully known. For this reason, thedimeric fat acid value determined by this method is slightly lower thanthe value determined by the micromolecular distillation method.Generally, the monomeric fat acid content determined by themicromolecular distillation method will be somewhat higher than that ofthe chromatography method. Because of the difference of the two methods,there will be some variation in the values of the contents of variousfat acid fractions. Unfortunately, there is no known simple directmathematical relationship correlating the value of one technique withthe other.

The polymeric fat acid based polyamides useful in the present inventionare prepared by conventional amidification procedures, usually heatingthe reactants to a tempe u e een .lQQiand. Q0C-. Prf a y 225-250 C. fora time sufficient to complete the reaction, generally 2-8 hours.Essentially molar equivalent amounts of carboxyl and amine groups areemployed in preparing the polyamide. As set forth above, the resins mayalso include copolymerizing diacids and the diamine component employedmay be a single diamine or a mixture of two or more different diaminereactants. In addition, small amounts of monomeric, monocarboxylic acidsmay be present. With regard to any of the acid components, any of theequivalent amide-forming deriatives thereof may be employed, such as thealkyl and aryl esters, preferably alkyl esters having from l-8 carbonatoms, the anhydrides or the chlorides.

The diamines which may be employed may be ideally represented by theformula mu R Nu,

where R is an aliphatic, cycloaliphatic or aromatic hydrocarbon radicalpreferably having from two to 40 carbon atoms. Likewise, R may containboth aliphatic and aromatic hydrocarbon groupings. Illustrativepolyamines are ethylenediamine, hexamethylenediamine,tetramethylenediamine, and the like, bis (aminoethyl)- benzene,cyclohexyl bis(methyl) amine), dimeric fat diamine, etc. And asindicated previously the diamine may be employed alone or in mixtures oftwo or more. The most preferred diamines are the alkylene diamineshaving two-six carbon atoms in the alkylene group and mixtures thereofwith dimeric fat amines.

The dimeric fat diamine, sometimes referred to as dimer diamine","dimeric fat amine" or polymeric fat acid diamine are the diaminesprepared by amination of dimeric fat acids. A suitable method ofpreparation is disclosed in U. S. Pat. No. 3,010,782.

The copolymerizing compounds commonly employed are aliphatic,cycloaliphatic or aromatic dicarboxylic acids or esters defined by theformulae:

R OOC (100R and R OOC-R"COOR where R" is an aliphatic, cycloaliphatic oraromatic hydrocarbon radical preferably having from one to 20 carbonatoms and R is hydrogen or an alkyl group, preferably having one toeight carbon atoms. Such acids include oxalic, malonic, adipic, sebacic,suberic and the like.

When copolymerizing dicarboxylic acids are employed with the polymerizedfat acids, it is preferred that the carboxyl groups from the polymericfat acid should account for at least 50 equivalent percent of the totalcarboxyl groups. Likewise, in those polyamides as previously describedprepared from an aminoacid and- /or a lactam with a dibasic acid and adiamine wherein dimeric fat acid is included, it is preferred that thecarboxyl groups from the dimeric fat acid should account for at least 50equivalent percent of the total carboxyl groups.

As indicated previously, the polyamide is dissolved in a solvent whichis capable of rapidly evaporating and sprayed from the solution to forma fibrous mat of the appearance shown in FIGS. 1 through 6. The solventsuseful in this invention are those which dissolve the polyamide resinand have an evaporation rate of less than 5.5, preferably less than 3.0.The term evaporation rate as used herein is defined as the" ratio oftime required for agiven volume of the sol vent to evaporate at i735 2F. and 50 f percent relative humidity when compared to the same volumeof diethyl ether which is assigned the value of one. A

suitable testing procedure is given in the Paint industry Magazine, Vol.76, No. 4, p. 15, April 196]. To determine whether or not a solventwould dissolve the id l? .ml2$ EY9 9f- SLl .Bl and polyamide was pacedin a conventional paint shaker for 1 hour of shaking. lf at the end ofthat time, the resulting mixture was not clear, the system wasdetermined to be incompatible. it has been found that chlorinatedhydrocarbon solvents with a suitable yaporatm rate work most sa ti sfactorily. Solvents can generally be classified into three categories;very useful solvents having an evaporation rate of less than 3.0,operable solvents having an evaporation rate of about 5.5-3.0, andunsuitable solvents having an evaporation rate of above 5.5.illustrative of evaporation rates of some representative solvents are listegl as follows:

Various mixtures of solvents can be used so long as they fall within thesuitable evaporation rate. For instance, small amounts of solvents whichby themselves would be within Groups ll or Hi can be mixed with natedhydrocarbons (Freon) and other commercial propellants with small amountsof alcohols which induce solubility and have the desired evaporationrate.

When spraying the polyarnide resins from the solvent mixtures asdescribed above, it has been found that the viscosity can significantlyinfluence the type of web effect obtained. Generally, the viscosity ofthe resin is a function of the molecular weight and is the determinantof solution viscosity and product performance. The fol lowing shows therelation of the spray solution viscosity ranges:

Low viscosity0.5l0.0 centipoises Medium viscosityl0.0-65.0 centipoisesHigh viscosity-65.0l00.0 centipoises Generally, a low viscosity, e.g.,O.5l0.0 cp., produces a finely divided fibrous spray which is solventsaturated when airborne in the spray. Since a large percentage of theatomized solvent is carried to and depos ited on the substrate, theshort resin fibers are partially redissolved giving a mat surface ofunusual continuity. Generally, it is necessary to obtain an optimumbalance between solids content of the solution, discharge rate andsolvent evaporation rate. it is also known that as the viscosityincreases, the solvent solution containing the resin becomes moredifficult to discharge and atomize and the resulting fibrous texture ofthe mat eventually resembles a spattering of individual globules.Likewise, the bulk density of the mat increases with an increase insolution viscosity. Also, as is shown in the examples, the higherviscosity resins result in greater tensile strength and betterelongation.

in order to use the fibrous mats as a decorative substance, it isdesirable to be able to obtain various colors. it has been found thatvarious colorants may be included in the solventresin mixture prior tospraying. Generally, hydrocarbon dyes are preferred over pigments.Suitable dyes include the Solvent series of dyes as listed in the ColourIndex, Society of Dyers and Colourists, 2nd Ed., 1956. Among the usefuldyes are those having azo groups, xanthene groups, anthraquinone andtriarylmethane groups. illustrative are the following: Solvent Red 26,C1. 26, 120: Solvent Green 3, Cl. 61, 565: Solvent Orange 7, CI. 12, 140wherein C.l. is the color index.

Various methods of spray application have been found to worksatisfactorily. These include air gun spraying, aerosol spraying, airbrush, and other conventional methods of spray application. The optimumspraying conditions can be easily obtained by simple spray testingtechniques. An important element for an aerosol application is properselection of the valve assembly. A useful nozzle is a Model 103 Newman-Green spray head having a 0.055 inch slot and a 0.060 inch orifice and avapor tap hole in the capillary dip tube enlarged to 0.050 inch. Othermethods of application will be readily apparent to those skilled in theart. a

The spraying is preferably accomplished using solution temperatures ofabout 50 to 100 F., and even more preferably ambient roomtemperatures-Le, about 7080 F. Also as indicated previously the sprayingis carried out employing at least 3 lb. gage pressure. The sprayingpressure varies as to the type of equipment, solution viscosity, etc.and the upper range may be quite high-Le, 100 lb. gage pressure andhigher. A preferred range is 35 to 45 lb. gage pressure. At any rate asufficient pressure is needed for the sprayed composition to reach thereceiving surface.

Likewise, the distance of the latter from the spray orifice can varywidely. Thus, such surface is sufficiently far away from the orifice toallow the formation of the fibrous pattern or mat. Solvent evaporationis also facilitated by increased distance. Preferably, the receivingsubstrate will be from about 1 to 3.5 feet from the spray orifice with adistance of 14 to 30 inches being especially preferred.

As mentioned previously, the polyamide fibrous mat may be self-supporting or sprayed onto a support which will form part of the finalarticle. When a selfsupporting mat is desired, it must be formed on amaterial of the type that would release the mat. Such supports includeTeflon, polished plate glass, metals, wire screens, or smooth surfacescontaining conventional release coatings. Likewise, the polyamide may besprayed onto various other substrates including paper, wood, metal,cotton, plastic film, synthetic fibers, etc.

A slight modification of the invention may be practiced by thermallytreating the fibrous mat. If the polyamide is heated to a temperatureslightly less than that at which the mat continuity is changed, thetensile strength and percent elongation are improved. Generally, thistemperature is different for each polymer but common laboratory testingtechniques will be readily apparent to those skilled in the art. Asshown in Example X, a suitable thermal treating temperature for theresin of Example X is approximately C. it is also possible for thefibrous mat to serve as an adhesive by heating the fibers to near orabove the melting point of the polymer. Various colored sections of themat may thus be attached to each other giving a checkerboard, decorativeeffect.

The sprayed polyamide fibrous mat of this invention may be useful as atextile material. For example, it has been found that the fibrous matmay be sprayed onto a cloth substrate. FIG. 7 shows a raincoat preparedfrom such material. Other uses include a coating for bottle caps to givea tamper-proof seal, paneling, decorative panels, creative art media,spary molded fabrics, wall covering, lampshades, decorative packages andpapers, surgical dressings, protective covering for cans, water proofingagent, etc. The fibrous mat may also be used to produce a cover for thetops of wine bottles thus eliminating the need of a more expensive metalcover. Additionally, the fibrous mats have insulative and accousticalproperties.

The fibrous mats of the invention also have the unique property offorming a bond when two or more layers thereof are simultaneouslysevered using a shearing action such as when out employing a commonscissors. This property is illustrated by FlGS. 12-15 wherein an objectis packaged by placing same between two layers of the fibrous mat andsimultaneously severing the two layers on all sides of the object. Thebond strength is usually less than the strength of the fibrous matfacilitating clean separation when desired at the point or length of thesaid bond. Where the shearing apparatus is heated above ambient roomtemperature such that the point of contact thereof with the fibrous matlayers during the shearing is above about F., the strength of the newlyformed bond between the two layers is increased. Decorative effects canbe achieved by utilizing different colored layers of the fibrous matwith the simultaneous shearing being in a pattern, predetermined orotherwise.

This invention is further illustrated by the following Examples whichare not to be considered as limiting.

EXAMPLE I A polyamide was prepared from polymeric fat acids (polymerizedtall oil fatty acids) and hexamethylenediamine by charging 111.5 lbs. ofthe polymeric fat acid into a flask along with 32.51 lbs. ofhexamethylenediamine. The polymeric fat acid had the followingproperties:

Monomer0.9 percent Intermediate-4.6 percent Dimer93.4 percent Trimer1.0percent Acid Value193 Saponification Value 1 96 iodine Value9.l

in addition to the above reactants, it is also possible to add anantifoaming agent as well as a color remover such as a percent solutionof phosphoric acid. In this example, 100 grams of the acid and 10 gramsofa commerically available antifoaming agent were added to thereactants. The above reactants were heated to 250 C. over a period of 2hours and the temperature was held at about 250 C. for 3.25 hours. Theresulting polyamide had the following analysis:

Acid Value (meq./l g.)7.6

Amine Value (meq./kg.)35.8

Tensile Strength, psi3,529

Yield Strength, psil,15l

Percent Elongation-571 Melt Index at 175 C.19.66 gm.

The melt index was determined according to ASTM D-l238-65T. A 10 gramsample of the above polyamide resin was then mixed with 90 grams ofchloroform. The mixture was shaken in a paint mixer until a resultingclear solution was obtained, approximately 30 minutes.

The mixed solution was then charged to a type CMSOl DeVilbiss spray gun.The spray gun pressure was set at lb.+ gaged pressure and the mixture(at ambient temperature) was sprayed onto a Teflon coated glass clothapproximately 20 inches from the spray orifice. The evaporation rate ofthe solvent resulted in the polymer being deposited on the cloth as astringy, tacky solid. The tackiness formed a continuity which renders adry tissue-like film. The film is in the form of a fibrous mat which canbe readily separated from the cloth and serves as a self-supportingfibrous mat. The fibrous mat had a density approximately 75 percent ofthat of a solid extruded film of the same polyamide.

EXAMPLE 11 A polyamide polymer was prepared as follows with a polymericfat acid having the following analysis:

Monomer-1.6 percent Intermediate-1.9 percent Dimer95.6 percent Trimer l.0 percent Acid Value-191 Saponification Value- 195 Iodine Value8.9

6 The fat acid, in an amount of 125.0 pounds, was re- 5 acted with 52.5pounds of 4,4'-diamino-3,3-dimethyl- (dicyclohexybmethane.

The above reactants were heated to 250 C. for 3 hours and thetemperature was maintained at 250 C. for 1 hour. A vacuum of 3 mm Hg wasthen applied and the temperature held at 250 C. for 5 hours undervacuum.

The resulting polyamide resin had the following analysis:

Acid Value--l3.3

Amine Value-44.4

Tensile Strength, psi4,998

Yield Strength, psi-4,219

Percent Elongation205 Inherent Viscosity-0.583

The inherent viscosity is the natural logarithm of the relativeviscosity divided by grams of the polyamide, generally 0.50 gm per ml.of solvent, chlorophenol.

The spray procedure of Example I was repeated and similar results wereobtained.

EXAMPLE III A polyamide was prepared as follows using a polymeric fatacid having the following analysis:

Monomer-0.6 percent lntermediate4.3 percent Dimer92.5 percent Trimer2.6percent Acid Valuel94 Saponification Value-l96 Iodine Valuel0.1

The fat acid, in an amount of 30 pounds, was reacted with the following:

Azelaic acid-1.308 lbs.

Hexamethylenediamine-6.027 lbs.

Ethylenediaminel .483 lbs.

The above reactants were heated to 250 C. for 3 hours and thetemperature was maintained at 250 C. for 1 hour. A vacuum of 3 mm Hg wasthen applied and the temperature held at 250 for 5 hours under vacuum.

The resulting polyamide resin had the following analysis:

Acid Value-1.3

Amine Value2.l

Tensile Strength, psi2,l02

Yield Strength, psi-719 Percent Elongation595 Brookfield viscosity at225 C.3 17 poise (No. 5 spindle at 4 rpm) The spray procedure of ExampleI was repeated and similar results were obtained.

EXAMPLE IV Example I was repeated except that the solvent used for thespraying application was methylene chloride. Results similar to those ofExample I were obtained.

EXAMPLE V The following solution,-Solution A, was prepared:

Polyamide from Ex. l gms.

Dichloromethane-600 gins.

Tetrahydrofuran220 gms.

Methanoll0 gms.

Gardner Viscosityat 25C.32 cps The ingredients to prepare Solution Awere placed in a paint shaker for 1 hour. Due to heat and pressuregenerated from the shaking, it was necessary to cool the mixingcontainer and contents to room temperature before opening.

After cooling the above mixture, three 98.0 gram samples were withdrawnand placed into four 6 02. glass jars. A separate 2 gm. l percent dyesolution was placed into each glass jar and the respective dyes andSolution A were mixed on the paint shaker for 15 minutes. The three dyeswere as follows:

Solvent Red 26, Color Index 26120 Solvent Green 3, Color Index 61565Solvent Orange 7, Color Index 12140 Each of the three mixtures weresprayed at 40 lb. gage pressure with the spray gun as in Ex. l, onto aseparate piece of Kraft wrapping paper. A decorative, artistic, colored,fibrous mat was obtained which remained adhered to the paper.

EXAMPLE VI A tamper-proof container was prepared by first preparing thefollowing spray solution:

Polyamide Resin of Ex. ll5 gms.

Dichloromethane-25 gms.

Tetrahydrofuran60 gms.

Methanoll gm.

Gardner Viscosity-32 cps The above ingredients were shaken in a paintshaker until a clear solution resulted, the solution was sprayed aroundthe cap of a one-ounce bottle. The solution was sprayed with a Model H,Paasche Airbrush at 25-40 psig. A tamper-proof seal was obtained similarto that shown in FIG. 10. The seal can be easily broken but cannot beresealed by melting, heating or by other means without a completere-spraying.

EXAMPLE Vll The following spray solution was prepared: Polyamide Resinof Ex. ll7 gms. Dichloromethane-60 gms.

Tetrahydrofuran22 gms.

Methanol-l gm.

Gardner Viscosity32 cps The spray solution was prepared in in Ex. VI andsprayed with an air gun as in Example I. The spray solution was appliedto the top of a beverage can to form a sanitary covering as shown inFIG. 8. The covering was easily removed without the use of a releaseagent.

The same formula was used to spray a paper except that TiO in an amountof 10 percent of the weight of the total solution was added for a whitebase. A decorative paper was thus obtained.

The spray solution of this Example was applied directly to a moldedlampshade to give a fibrous mat effect to the lampshade.

The spray solution was also applied to a brassiere form in which thecups were formed from filamentspray, fibrous mat. The straps andfastenings were of conventional construction.

EXAMPLE VIII A piece of highly sized cotton material of the typecommercially available in a yard goods store was sprayed with thepolyamide solution of Example VII. The spray solution was applied withan air gun as in Example l. Coverage of the spray was such that 1 14grams of the dryed sprayed solution covered 2 square yards of thefabric. The sprayed cotton fabric was then cut and made into a raincoatas shown in FIG. 7. The raincoat was water repellent.

EXAMPLE IX The following Example will illustrate the relative tensilestrengths and percent elongation of the fibrous mat for variousviscosity polymers. The polyamide resin used was that of Example lexcept that the viscosity for the three samples was varied as indicatedbelow. The spray solution was prepared as indicated in the Table below.Each solution was prepared by weighing 100 gram samples into a 6 ounceglass jar, tightly sealed, and then placed in a paint shaker for 1 hour.The solutions were then sprayed onto Teflon coated glass cloth with thespray gun as used in Example 1. The pressure was set at 35 psig and thespray gun was held approximately 20 inches from the substrate and aspraying stroke of about 18 inches used to apply the solution. All ofthe sample was sprayed onto the substrate. The mat was removed from thesubstrate and cut into strips 1 inch X 3 inch. The cut strips were thenweighed amd the mat weight determined in gram/sq. in. To determine thetensile strength, the strips were placed between the jaws of an lnstronTester, Model TM, lnstron Eng. Corp., Canton, Mass. The strips wereplaced so as to have exactly 1 inch of mat between the jaws, i.e., a jawgap of l inch. The tester was set at a crosshead speed of 0.5 inch/min.The tensile strength is defined as the maximum load in grams for failureof the mat per mat weight in grams/area, i.e., gmfin Therefore, thetensile strength will have the units gms/gm/in. The elongation becomes adirect reading of the distance of travel. The results are summarized inTables I and ll below. The mat weights marked with an asterisk indicatesthat 50 gram samples were sprayed rather than 100 gram samples.

TABLE I Resin A B C Resin Viscosity (Brookfield 250 p 180 p No. 5spindle, 4 rpm, 205C.) Melt lNdex at 175F. l9.66 gm. Resin Amt. (gms.)l5 l5 l0 Dichloromethane (gms.) 60 60 60 Methanol (gms.) l l lTetrahydrofurar! (gms.) 24 24 29 Gardner Viscosity, of the Resin B ofExample [X was tested to determine the effect of thermally treating thesprayed fibrous mat. The sprayed fibrous mat comprised of Resin B inExample lX was cut into 1 inch X 3 inche pieces and each piece weighed.The samples were then subjected to thermal treating by heating thesamples to 50 C., C., C., and C. respectively for 1 hour at the varioustemperatures. The effect on the tensile strength and percent elongationis summarized in Table lll. lt

was found that the fibrous mat was generally destroyed at 90 C. orabove.

TABLE III Sample Sample Tensile Strength Elongation C. Wt. gms gm/gm/inControl 0.2060 1 100 27 50C. 0.2035 1073 19 75C. 0.2045 1214 16 80C0.2030 1379 26 85 0.2055 1281 35 It can been seen that generally heattreatment increases the tensile strength.

EXAMPLE XI The following spray solution was prepared for aerosolapplication:

Polyamide Resin, Ex. ll8.0 gms.

Dichloromethane40.0 gms.

Tetrahydrofuran27.0 gms.

Methanol15.0 gms.

Gardner Viscosity of the solvent mixture at 25 C.32.l cps This solutionwas prepared by charging the materials into a 6 ounce glass jar andplaced in a paint shaker for 1 hour. A 60 gram sample of the solutionwas weighed into a standard 10 ounce tinplate aerosol container. Thecontainer was sealed with a Newman-Green valve having the followingdescription: Model R-70-l 18, with a 0.030 inch capillary tubing, Epon(B 5.0) and a 0.060 inch vapor tap hole, 70 Durometer Buna gasket and astainless steel spring. The container was injection filled with 40 gramsof dichlorodifluoromethane (Freon-12) which pressurized the container to40 psig. The spray head was a Model 103 Newman-Green sprayhead having a0.055 inch slot and a 0.060 inch orifice. The solution was sprayed ontoa paper substrate and a fibrous mat was formed on the substrate.

EXAMPLE XII In this and the following Example Xlll, the nylon copolymersused were members of the Elvamide series of nylon resins by E. l. DuPontde Nemours.

EXAMPLE XIII Example X11 was repeated except that the following solutionwas prepared:

Nylon copolymer resinl2.5 gms.

Dichloromethane-40.0 gms.

Tetrahydrofuran- 10.0 gms.

Methanol-37.5 gms.

Gardner Viscosity at 25 C.- cps The nylon copolymer resin of thisexample was nylon 650 percent nylon 6,620 percent nylon 6,1020 percentnylon 11 (made from ll-aminoundecanoic acid)-l0 percent Results similarto Example XII were obtained.

EXAMPLE XIV Self-supported fibrous mats as prepared in Example I weretested for the formation of bonds by laying two 1 inch by 3 inch stripsface to face and then severing the same by cutting across the width ofone end of the two layers (approximately 1 inch from the end) using ascissors, either at ambient temperature (77 F.) or at 160 F. (thescissors were heated by soft soldering a U4 inch by 4 inch, wattcartridge heater to each blade using a powerstat regulated to produce aline voltage of 2528 volts). The cutting produced in each instance twobonded strips having lengths of approximately 2 and 4 inches (half ofthe length being contributed by each layer). The bond strength wasmeasured using an Instron Tensile instrument at a crosshead speed of 0.5inches/min. and a gap space between the positioning jaws of 1 inch. Thestrength of the bond formed using the scissors at room temperature was217 grams (load at failure). The F. heated scissors bond had a strengthof 353 grams (load at failure).

This invention offers a very economical selfsupporting or supportedfibrous mat which has multiple uses including textile materials,decorative uses, and any other number of applications which will bereadily apparent to those skilled in the art. Since the mats areextremely drapable, they will be useful in many types of complexapplications.

Now, therefore, 1 claim:

1. An air pervious and water repellent polyamide fibrous mat comprisedof fibers which are essentially non-uniform in thickness and length andwhich have along their length a number of non-uniform totally enclosedair pockets, said fibrous mat having been prepared by spraying asolution of a polyamide dissolved in a solvent having an evaporationrate of 5.5 or less onto a support at a gage pressure in excess of 311)., said polyamide being selected from the group consisting of (1)copolymers of self-condensed aminolactams or aminoacids or mixturesthereof and the condensation products of dicarboxylic acids and diaminesand (2) polymers of the condensation products of polymeric fat acids anddiamines and said fibrous mat being further characterized as beingself-supporting when released from a support backing therefor.

2. The fibrous mat of claim 1 wherein the polymeric fat acid ispolymerized tall oil fatty acid.

3. The fibrous mat of claim 2 wherein the polymeric fat acid has a dimeracid content of at least 80 percent by weight.

4. The fibrous mat of claim 1 wherein the diamine has the formula of l-lN-R-l\l1-l wherein R is an aliphatic, cycloaliphatic oraromatichydrocarbon radical of 2-40 carbon atoms.

5. The fibrous mat of claim 1 wherein the polyamide is selected from thegroup consisting of a. the reaction product of polymerized tall oilfatty acid and hexamethylene diamine,

b. the reaction product of polymerized tall oil fatty acid and4,4-diamino-3,3-dimethyl (dicyclohexyl) methane,

c. a copolymer of polymerized tall oil fatty acid, azelaic acid,hexamethylenediamine, and ethylenediamine,

d. a copolymer of epsilon-caprolactam, adipic acid andhexamethylenediamine, and sebacic acid and hexamethylenediarnine, and

e. a copolymer of epsilon-caprolactam, adipic acid andhexamethylenediamine, sebacic acid and hexc x sn i mins, and ungs noicacid.

6. The fibrous mat of claim 1 wherein the polyamide solution contains atleast five percent by weight of dissolved polyamide.

7. The fibrous mat of claim 6 wherein the solvent is a chlorinatedhydrocarbon solvent.

8. The fibrous mat of claim 7 wherein the solvent is methylene chloride.

9. The fibrous mat of claim 7 wherein the solvent is chloroform 10. Thefibrous mat of claim 7 wherein the solvent is methyl chloroformv 11. Thefibrous mat of claim 6 wherein the solvent is a mixture of solvents.

12. The fibrous mat of claim 11 wherein the solvent is a mixture oftetrahydrofuran containing up to 0.3 parts by weight of methanol perpart of tetrahydrofuran.

13. A process of forming a bonded article which comprises simultaneouslyshearing at least two layers of the fibrous mat of claim 1 while thelayers are in contact.

a: a: a

2. The fibrous mat of claim 1 wherein the polymeric fat acid ispolymerized tall oil fatty acid.
 3. The fibrous mat of claim 2 whereinthe polymeric fat acid has a dimer acid content of at least 80 percentby weight.
 4. The fibrous mat of claim 1 wherein the diamine has theformula of H2N-R''-NH2 wherein R'' is An aliphatic, cycloaliphatic oraromatic hydrocarbon radical of 2-40 carbon atoms.
 5. The fibrous mat ofclaim 1 wherein the polyamide is selected from the group consisting ofa. the reaction product of polymerized tall oil fatty acid andhexamethylene diamine, b. the reaction product of polymerized tall oilfatty acid and 4,4''-diamino-3,3''-dimethyl (dicyclohexyl) methane, c. acopolymer of polymerized tall oil fatty acid, azelaic acid,hexamethylenediamine, and ethylenediamine, d. a copolymer ofepsilon-caprolactam, adipic acid and hexamethylenediamine, and sebacicacid and hexamethylenediamine, and e. a copolymer ofepsilon-caprolactam, adipic acid and hexamethylenediamine, sebacic acidand hexamethylenediamine, and 11-aminoundecanoic acid.
 6. The fibrousmat of claim 1 wherein the polyamide solution contains at least fivepercent by weight of dissolved polyamide.
 7. The fibrous mat of claim 6wherein the solvent is a chlorinated hydrocarbon solvent.
 8. The fibrousmat of claim 7 wherein the solvent is methylene chloride.
 9. The fibrousmat of claim 7 wherein the solvent is chloroform.
 10. The fibrous mat ofclaim 7 wherein the solvent is methyl chloroform.
 11. The fibrous mat ofclaim 6 wherein the solvent is a mixture of solvents.
 12. The fibrousmat of claim 11 wherein the solvent is a mixture of tetrahydrofurancontaining up to 0.3 parts by weight of methanol per part oftetrahydrofuran.
 13. A process of forming a bonded article whichcomprises simultaneously shearing at least two layers of the fibrous matof claim 1 while the layers are in contact.